1. Field of the Invention
The present invention relates to a workpiece transfer apparatus for loading and unloading a workpiece into and from a machine tool.
2. Description of the Prior Art
In the known workpiece transfer apparatus utilizing a single crank motion mechanism, the crank arm having the crank pin spaced a distance from the axis of the crank arm is rotated about its axis. The connecting member is pivotably connected at its one end to the crank pin and pivotably connected at its other end to the workpiece support device. The workpiece support device is moved straight along the guide device in accordance with the crank motion of the crank arm. With this arrangement, the distance between the axes of the crank arm and the crank pin has to be large enough to assure a predetermined straight stroke of the workpiece support device, which necessarily results in the larger width of the apparatus.
Furthermore, the workpiece support device is applied with a component force perpendicular to the direction of straight movement thereof during rotation of the crank arm, so that the guide device guiding the straight movement of the workpiece support device may lose its expected function.